It is well known that inflatable articles inflated with air tend to go flat in a very short period of time ranging from a few days to a few weeks. Obvious examples include the deflation of party balloons or the need to re-inflate soccer balls between weekly matches. In fact, most traditional or conventional game balls lose air over time and fall out of game specifications within weeks or months. For example, traditional basketballs lose over fifty percent (50%) of their air pressure in just one year.
One cause of such fast loss of inflation pressure is due, in part, to seepage of gas molecules through the ball membranes due to, among other things, seam defects, defective materials, and defective construction techniques, including incomplete cure and degradation of the polymer, resulting in bladder seam leaks.
Another cause of such inflation pressure loss is poor valve construction. Some if not all inflated articles have “passive” self-sealing valves, which use a valve construction and design to provide a passageway for a seal breaking device such as a ball inflation needle. The seal itself is achieved by means of a cut slit forming two flat parallel surfaces that are squeezed together by circumferential forces delivered by means of fitting an elastomeric valve body into a surrounding elastomeric housing that is tapered towards the bottom and designed to apply an interference fit. The application of this force, created by the valve housing constraining the valve body, helps squeeze the two parallel seal surfaces together. Unfortunately when the inflation needle is inserted or removed from this configuration it can induce dirt into the seal surface passageway or create uneven stress gradients in the rubber or elastomeric material of the seal surfaces that create micro-channels for air or inflation gas to directly escape to atmosphere. Another cause would be cut defects in the valve seal surfaces from using inadequately sharpened blades or a misalignment in the valve mold register during the seal passage cutting process. All these problems with the valve and seal system can cause the ball or inflated article to rapidly loss pressure.
It is known in the art that the use of large molecule gases (either alone or in combination with air or other gases) improves pressure retention in inflatable articles. Examples of such uses can, for instance, be found in the following issued U.S. Pat. Nos. 4,098,504; 4,300,767; 4,340,626; 4,358,111; 4,513,803; 5,227,103; 5,356,430; 5,578,085; and 6,457,263.
As is well known in the art, however, when inflatable articles are filled with a more dense non-air gas and are subjected to impacts, for example while bouncing a ball, the component and/or material configurations along with hard shell or dimensional attributes and the in-use environments are conducive to the generation of increased levels of noise from the article (see for example U.S. Pat. No. 4,300,767). In most instances, the noise level is increased for particular frequencies in the overall sound spectrum of the inflatable article. The decibel level of these affected frequencies can make the inflatable articles sound unpleasant, creating a ringing, pinging or otherwise sound that is considered unsuitable for the desired article's use, environment or consumer appeal. Attempts have been made to minimize this problem. For instance, Reed et al., as set forth in U.S. Pat. No. 4,300,767, discloses a method of dampening unwanted acoustic resonance caused by the use of SF6 in the inflated article. The problem however was not fully solved as the solution of Reed et al. only addresses resonant frequencies greater than 2000 Hz. However, there are significant resonant frequencies occurring at the 0-2000 Hz range which are not absorbed by the Reed et al. solution. While such resonant frequencies become more and more noticeable as the size of the inflatable object increases, even in smaller balls, low resonating frequencies are still present. Further, and perhaps more importantly, the solution of Reed disrupts the symmetry of the inflatable article, in Reed's case, a tennis ball.
When inflated articles are inflated with a gas mixture other than air for the purpose of providing long term inflation and pressure control of the inflated article, however, they have a tendency to induce a significant change in performance as a result of the gas mixtures' deviation from typical air properties. For example, the feel of a soccer ball filled with a gas mixture comprising a large bulky, low permeability gas gains liveliness or, the shock absorption or bounciness of a bicycle tire changes when it is filled to its normal riding pressure with a low permeability gas mixture. These changes make the final inflatable article unsuitable because of feel, touch, comfort, control and other tactile or sensual effects that comprise a person's appreciation for comfort, playability and suitability. Such changes in the inflatable article's weight, apparent hardness, bounciness, liveliness and comfort can be become reasons for unsuitability.
There is thus a clear need for inflatable articles that remain inflated for extended periods of time, and that are inflated by a method resulting in pressure control, wherein these articles emanate minimal or, more preferably, undetectable pinging or ringing noises upon impact and retain standard, accustomed-to liveliness or playability characteristics.